In September 2019, a very large WW2 bomb was encountered by engineers in north-western Poland. It was discovered in a busy Polish shipping channel. Now, a year on, a plan has been confirmed to neutralise the threat.

In mid-October, Polish divers will start work on neutralising the weapon at the bottom of the Piastowski Canal in Swinoujscie. An explosive will be fired at the weapon, a technique known as deflagration. 

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The unexploded bomb was originally found by employees of a German company carrying out work to deepen the Piast Channel. Poland’s 8th Coastal Defence Flotilla and its navy divers carried out reconnaissance and analysis of the suspicious object.  The huge device was identified as a British RAF ‘Tallboy’ bomb.

Work has been going on in the channel for some time and this is not the first British wartime bomb to be found in the channel. Two British air-dropped naval mines were also found in 2019.

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Post-raid photograph showing craters from Tallboy bombs near the Lützow.
UXO Contamination Incident

On 13th April 1945, 24 Avro Lancaster bombers attacked the German cruisers Lützow and Prinz Eugen. However, this raid was unsuccessful due to cloud cover. The former was anchored in the Piast Channel.

Then on the 16th April 1945, the famous Dambusters Squadron dispatched 18 Lancasters for a second attempt. The entire squadron dropped Tallboy bombs. These unguided weapons were dropped from high altitude and therefore most missed their target.

They scored several near misses which caused Lützow to sink. However, the water was shallow enough that her main deck was still 2m above water.  This UXO find is therefore highly likely to have been dropped during this raid.

The Tallboy

This British freefall bomb was developed and deployed during WW2.  It was second only in size to the RAF’s Grand Slam bomb. At 5.5-tonnes, it was designed to create a seismic shock by detonating a huge charge deep underground. When it initiated an earthquake effect would shatter the target.

The Tallboy was designed to be dropped from an optimal altitude of 18,000ft at a forward speed of 170mph, striking at 750mph. It made a crater 80ft deep and 100ft across and could penetrate 16ft of concrete.

The bomb weight and the high altitude required meant that the Lancasters had to be specially adapted. Armour plating and guns were removed to reduce weight, and the bomb-bay doors were modified.

These bombs were more than twice the mass of the largest Luftwaffe general purpose ‘iron’ bomb dropped on the UK.

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Diagram of the Tallboy bomb.